Thank you for your request.
Unfortunately, at the moment there is no way to "fit to width" and "fit to height" and "100% fit" via js triggers. You can set these parameters only in application.properties file. Please check this article
for load helper parameters.
About displaying number of pages. You can independently reorder css styles for Viewer window to achieve the result that you want. The Viewer library doesn't provide any specific methods or events for this.
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